Micro-abrasive blasting device and method for advanced flow-control

ABSTRACT

The present invention is a superior micro-abrasive blasting device ( 55 ) with a flow-control mechanism ( 65 ) and a flow-actuated discharge conduit seal ( 80 ). Flow-control is achieved through the deformation of discharge conduit ( 10 ) to control the opening of discharge conduit ( 10 ). The flow-control mechanism ( 65 ) provides for the continuous pressurization of the mixing chamber ( 23 ) to yield instantaneous flow start-up response and instantaneous flow shut-off response.  
     Flow-actuated discharge conduit seal ( 80 ) is optimally disposed at discharge conduit inlet ( 12 ) and is normally shut when no flow is present. The operation of flow-actuated discharge conduit seal ( 80 ) prevents the entry of particulate matter ( 20 ) into discharge conduit ( 10 ) when no flow is present, for either when mixing chamber ( 23 ) is pressurized or depressurized.  
     A method is provided for maintaining discharge conduit outlet ( 70 ) stationary with respect to target material ( 40 ) while flow-control mechanism ( 65 ) is actuated. The method utilizes the deformation properties of discharge conduit ( 10 ) to provide the necessary compliance so the discharge conduit outlet ( 70 ) remains stationary.  
     An additional method is provided for preventing the entry of particulate matter ( 20 ) into discharge conduit ( 10 ) when no flow is present. The method utilizes a mechanism mounted onto discharge conduit ( 10 ) that seals discharge conduit ( 10 ) when no is present, yet opens when there is flow through micro-abrasive blasting device ( 55 ).

BACKGROUND OF THE INVENTION

[0001] The present invention relates generally to the field of devices for propelling particulate matter with intent to etch the surface of a target material. More specifically, the present invention relates to a micro-abrasive blasting device powered by a pressurized-gas source for use with dental procedures.

[0002] Abrasive blasting devices operate on the physical property that gas at a higher pressure flows towards and into gas at lower pressure. When particulate matter is mixed with gas at higher pressure, the gas carries the particulate matter as the gas accelerates and flows to the lower pressure. As the gas and particulate matter blast the target material at high speed, the impact of the particles removes layers of the target material.

[0003] This process of material removal is commonly known as etching and also as sandblasting. As the rate of the target material removal increases, the etching process can be utilized for drilling and cutting. More specifically, the aggressiveness of the particulate impact-speed and frequency determine the rate of material removal, and thus whether an abrasive blasting device is useful for polishing, etching, or drilling. Particulate impact-speed and impact-frequency are adjusted by variation of the gas flow rate and gas-to-particulate mixture ratio.

[0004] In dentistry this technology is known as micro-abrasion and is used to achieve a variety of goals—such as to remove foreign material or to dull a shiny surface, roughen or etch the surface to enhance bonding quality, and to remove decay by drilling and cutting tooth structure. Such delicate procedures performed intra-oral require instantaneous response and precise control over the flow of the particle stream to prevent damage due to over-etching or material scatter.

[0005] Existing micro-abrasion devices for dental can be categorized into two functional groups that utilize two types of mechanisms for device flow-control.

[0006] 1. The first group utilizes an integral flow-control mechanism mounted on the abrasion device—such as utilized by the Paasche device, U.S. Pat. No. 2,441,441, Fernwood et al. device, U.S. Pat. No. 4,941,298, Sharp et al. device, U.S. Pat. No. 5,941,702, Jones et al. device U.S. Pat. No. 2,577,465, and Groman devices U.S. Pat. No. 6,347,984 and pending US patent of continuation-in-part application Ser. No. 09/897,286.

[0007] 2. The second group utilizes an external flow-control mechanism—such as required by the devices of Hertz, U.S. Pat. No. 5,839,946, its continuation-in-part U.S. Pat. No. 6,287,180, Hertz et al., U.S. Pat. No. 6,293,856, Schur et al., U.S. Pat. No. 6,004,191, Trafton et al., U.S. Pat. No. 6,354,924, and Stark et al., U.S. Pat. No. 4,475,370.

[0008] The integral control type mechanism is typically actuated via the user's finger-touch while the external control type mechanism is usually implemented in the form of a remote foot-pedal.

[0009] From group two, recently issued Hertz, Hertz el al., and Trafton et al. disclose handheld micro-abrasion tools that are controlled solely via an external flow-control mechanism. The Hertz continuation-in-part patent of U.S. Pat. No. 5,839,946 discloses additional details about the configuration of the original Hertz device. As in the original apparatus, the devices relies on a compressed-gas source engaged to the gas receiving port for means of propellant and flow control (Col. 3, lines 46-51 and Col. 7, lines 31-51). Hertz el al., discloses a multi-conduit particulate matter propelling apparatus that utilizes a multi-conduit source connector. The device is powered via a plurality of pressurized sources while flow control is provides via a valve apparatus upstream of the multi-conduit source connector (Col. 7, lines 18-44). The Trafton et al. device is similar to the Schur et al. and Stark et al. devices, and provides means for replenishing the abrasive material and a replacing the cannula. The Trafton et al. device also attaches to a pressure line upstream of the mixing chamber, and is operated via an on-off control apparatus and/or a foot-pedal (Col. 4, Lines 53-56). None of these embodiments provide means for preventing abrasive material from entering the discharge conduit.

[0010] From group one, recently issued Sharp et al. discloses a dental air-abrading tool with an integral flow-control mechanism (Col. 6, Lines 53-65). The Sharp et al. device provides for a sliding valve flow-control mechanism that is mechanically similar to the control valves of the Passche (Col. 3 Lines 14-23) and Jones et al. (Col. 2, Line 7-15), but differs from the Fernwood et al. pinch lever mechanism (Col. 2 lines 58-64). However, the Sharp et al. flow-control mechanism is operationally the same as the Passche, Jones et al., and Fernwood et al. devices, in that these valves reside on the pressurized-gas delivery conduit upstream of the mixing chamber. None of these embodiments provide means for preventing abrasive material from entering the discharge conduit.

[0011] As disclosed in the applicant's issued U.S. Pat. No. 6,347,984 and pending US patent of continuation-in-part application Ser. No. 09/897,286, filed Jul. 2, 2001, great advantages are derived over existing abrasion devices by means of

[0012] 1) preventing the abrasive material from entering the discharge conduit while there is no flow through the device, and

[0013] 2) superior flow-control and regulation via manipulation of the discharge conduit.

[0014] The embodiments previously disclosed by the applicant utilize integral flow-control to successfully employ these two objectives while not perturbing the critical operational parameter of distance between the discharge conduit outlet and target material.

[0015] The preferred embodiments of this inventor's prior art are shown in FIGS. 1, 2, and 3. These devices have the flow-control occurring at the inlet of the discharge conduit because that also prevents particulate matter from entering the discharge conduit while there is no flow through the device. However, in the realization of these embodiments to operate with conventional dental control methods the inventor has identified shortcomings. These shortcomings have been turned into opportunities that have lead to significant improvements over prior art.

[0016] The invention disclosed herein solves the following shortcomings with the current discharge conduit located flow-control devices:

[0017] 1. Referring to prior art FIGS. 1 and 2, both of these embodiments achieve flow-control means at the discharge conduit inlet via relative displacement of components. It is essential in these embodiments that the displaced components provide a seal to maintain the chamber pressure while being exposed to the abrasive material. Referring to FIG. 1, the interface of the chamber end wall and the chamber side wall requires that their surfaces slide with respect to each other. In FIG. 2, sliding surfaces are required at the interface of the discharge conduit port and the discharge conduit.

[0018]  Since dental devices require precise operational control, the relative motion of these surfaces must be smooth, reliable, and consistent. The exposure of the moving surfaces to the fine abrasive particles within the chamber makes these moving surfaces challenging to implement to these requirements.

[0019]  This is especially true when the chamber walls are fabricated of materials—such as plastics and/or silicon rubber—that are softer than the particulate matter. Additionally, the mixing action of the abrasive material may scratch or imbed particles in the chamber wall surfaces, leading to increase in surface roughness. Thus as the device is utilized, the smooth motion between the surfaces deteriorates and becomes less reliable.

[0020] 2. FIG. 3 shows a prior art embodiment that does not utilize the relative movement of chamber wall surfaces for means of flow-control. For this embodiment the flexing of the discharge conduit, via pinching, provides very effective flow-control means. However, since the discharge conduit pinch position is located downstream of the discharge conduit inlet, the embodiment is susceptible to particulate matter accumulation in the portion of the discharge conduit between the discharge conduit inlet and the discharge conduit pinch location. The abrasive accumulation occurs when there is no flow either when the mixing chamber is pressurized or depressurized.

[0021]  If abrasive is trapped in the discharge conduit, the initial pressurized-gas application causes the trapped abrasive to be released in a dense clump. This abrasive clump release causes an initial puff of abrasive that is inconsistent with the normal pace of particulate delivery during the device operation. This initial blast of abrasive may also damage the target surface by over etching. The prior art embodiment of FIG. 1 provides a cap at the discharge conduit inlet, but the cap only functions to seal the discharge conduit prior to device use. Once the cap is removed from the discharge conduit it no longer functions to seal the discharge conduit.

[0022]  As disclosed in the applicant's issued U.S. Pat. No. 6,347,984 and pending US patent continuation-in-part application Ser. No. 09/897,286, filed Jul. 2, 2001, flow-control mechanisms—such as on-off valves, flow regulators, and check-valves, etc.—have been widely utilized in air abrasion devices. However, dental devices that require very precise control and high operational safety, benefit most by having the flow-control mechanism on the discharge conduit.

[0023]  The Schur et al. and Trafton et al. devices attempt to improve the operation of their foot-pedal operated devices via the placement of a check valve at the pressurized-gas supply connector. Schur et al. (Col. 5 Lines 19-24) and Trafton et al. (Col. 9 Lines 14-46) disclose a check valve to restrict the flow direction through the connector and thus prevent abrasive material escape out of the device. However, in application this solution actually deteriorates the operational safety of the device, by forcing the device to continue operation once the foot-pedal has been released while the mixing chamber depressurizes. Additionally, it does nothing to prevent abrasive material entry into the discharge conduit.

[0024] 3. The advantages of prior art integral flow-control devices are not applicable when these devices are operated with standard dental chair external control mechanism, such as a foot-pedal. This is a disadvantage since dentists are very accustomed to operate a foot-pedal control mechanism, given that it is a standard control for dental hand-pieces.

[0025]  When pressurized-gas is provided to micro-abrasive devices with an integral flow-control mechanism downstream of the mixing chamber, the mixing chamber is pressurized and the device is ready for operation via the integral flow-control i.e. finger-touch control. Manipulation of any flow-control mechanism upstream of the mixing chamber does not affect the device since the operation is dictated by the integral flow-control downstream of the mixing chamber. Therefore, when a flow regulation valve—such as in a standard foot-pedal mechanism—is located external to the device, the micro-abrasive device is not operational until both the finger-touch control mechanism and the foot-pedal are activated simultaneously.

[0026]  The need to simultaneously activate the foot-pedal and the finger-touch control mechanism is cumbersome for the user and may yield unpredictable flow characteristics that could damage the target material. If the user keeps the integral flow-control mechanism open in order to achieve flow-control with the foot-pedal, then the discharge conduit flow-control mechanism is bypassed and its advantages lost. When the finger-touch control is bypassed, the device is reduced to the equivalence of the externally flow-controlled Hertz, Schur et al., and Trafton et al. devices. These externally flow-controlled micro-abrasive devices continue to operate while the mixing chamber pressure is depleted and allow particulate matter to accumulate in the discharge conduit.

[0027] In addition, previously disclosed integral flow-control devices have not maximized the benefits attained from flow regulation via manipulation of the discharge conduit.

BRIEF SUMMARY OF THE INVENTION

[0028] Accordingly, several objects and advantages of the present invention are:

[0029] (a) to provide a device with flow-control means located on the discharge conduit that is not dependent on the relative movement of components that are exposed to abrasive material.

[0030] (b) to provide a device with advanced means of preventing particulate matter from entering the discharge conduit when there is no flow.

[0031] (c) to provide a device with flow-control means located on the discharge conduit downstream of the discharge conduit inlet with means to prevent abrasive material from entering the discharge conduit when there is no flow.

[0032] (d) to provide a device with means to prevent particulate matter from entering the discharge conduit when there is no flow, that supports integral and/or external discharge conduit flow-control regulation.

[0033] Additionally,

[0034] (a) to provide a device configuration that facilitates increased chamber space for abrasive material and reduced mixing resistance.

[0035] (b) to provide a device that has a reduced number of components so device manufacturing and assembly complexity is reduced.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0036] Various other objects, advantages, and features of the invention will become apparent to those skilled in the art from the following discussion taken in conjunction with the following drawings, where closely related figures have the same number but different alphabetic suffixes:

[0037]FIGS. 1, 2, and 3 are cross-sectional side views of prior art micro-abrasive blasting devices with integral flow-control.

[0038]FIG. 4 is a cross-sectional side view of the micro-abrasive blasting device with integral flow-control means via deformation of the discharge conduit inlet while maintaining the discharge conduit outlet stationary. The pressurized-gas source is omitted for clarity.

[0039]FIG. 5 is cross-sectional side view of the micro-abrasive blasting devices with integral flow-control means and enhanced discharge conduit configuration. The pressurized-gas source and abrasive material are omitted for clarity.

[0040]FIG. 6 is a cross-sectional side view of the micro-abrasive blasting device with integral flow-control means, plus means to prevent particulate matter from entering the discharge conduit when there is no flow.

[0041]FIG. 7 is a cross-sectional side view of the micro-abrasive blasting device with alternative means of preventing particulate matter from entering the discharge conduit when there is no flow. The pressurized-gas source and particulate matter are omitted.

[0042]FIG. 8 is a cross-sectional side view of a micro-abrasive blasting device with no flow-control means on the discharge conduit, but with means to prevent abrasive material from entering the discharge conduit when there is no flow. The pressurized-gas source is omitted.

[0043]FIG. 9 is a cross-sectional side view of the micro-abrasive blasting device with a configuration that provides more abrasive material storage space and less mixing resistance.

[0044]FIG. 10 is a cross-sectional side view of the micro-abrasive blasting device with significant structural simplifications. The pressurized-gas source is omitted.

[0045]FIG. 11 is a cross-sectional side view of the micro-abrasive blasting device with configuration enhancements that simplify manufacturing. The pressurized-gas source is omitted.

[0046]FIG. 12 is a cross-sectional side view of the micro-abrasive blasting device with flow-control means operational via an external actuator mechanism.

[0047]FIG. 13 is a cross-sectional side view of the micro-abrasive blasting device with flow-control means that supports both an integral and external flow-control mechanisms.

[0048]FIG. 14 is a cross-sectional side view of the micro-abrasive blasting device with flow-control means operational via an integral or external actuator mechanism.

REFERENCE NUMERALS IN DRAWINGS

[0049]10 discharge conduit

[0050]12 discharge conduit inlet

[0051]15 mixing chamber side wall

[0052]17 mixing chamber first end wall

[0053]20 particulate matter

[0054]23 mixing chamber

[0055]25 gas-delivery conduit

[0056]30 mixing chamber second end wall

[0057]35 gas-receiving port

[0058]40 target material

[0059]45 discharge port

[0060]50 spring mechanism

[0061]55 micro-abrasive blasting device

[0062]60 actuator mechanism

[0063]65 flow-control mechanism

[0064]70 discharge conduit outlet

[0065]74 discharge conduit compliant segment

[0066]76 discharge conduit firm segment

[0067]80 flow-actuated discharge conduit seal

[0068]90 pressurized-gas source connector

[0069]95 external actuator mechanism

[0070]98 integral actuator mechanism

[0071] C control location

[0072] S seal location

[0073] F_(A) actuation force

[0074] F_(S) sealing force

[0075] F_(T) shutting force

DETAILED DESCRIPTION OF THE INVENTION

[0076] As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure.

[0077] Reference is now made to the drawings, wherein like characteristics and features of the present invention shown in the various FIGURES are designated by the same reference numerals.

[0078] Referring to FIG. 4A, a micro-abrasive blasting device 55 is disclosed. Micro-abrasive blasting device 55 includes a mixing chamber 23 having a mixing chamber side wall 15, a first end wall 17, and a second end wall 30. A particulate matter 20 is disposed in mixing chamber 23.

[0079] A gas-receiving port 35 is disposed in mixing chamber second end wall 30. A gas-delivery conduit 25 is in fluid communications with gas-receiving port 35, and extends through gas-receiving port 35 into mixing chamber 23.

[0080] A discharge port 45 is disposed in mixing chamber first end wall 17. A discharge conduit 10, elongated from discharge conduit inlet 12 to discharge conduit outlet 70, extends in fluid communications through discharge port 45 external to mixing chamber 23. Discharge conduit 10 is a combination of a discharge conduit compliant segment 74 and a discharge conduit firm segment 76. Of course as a design choice, discharge conduit compliant segment 74 and discharge conduit firm segment 76 could be integrated into a single contiguous conduit.

[0081] A spring mechanism 50 is attached to micro-abrasive blasting device 55 internally to mixing chamber 23. Spring mechanism 50 is pre-loaded and applies sealing force F_(S) onto discharge conduit 10 so discharge conduit inlet 12 is pinched at discharge conduit seal location S between spring mechanism 50 and mixing chamber side wall 15. As discharge conduit inlet 12 is pinched at seal location S, particulate matter 20 is prevented from entering discharge conduit 10.

[0082] The amount of sealing force F_(S) applied by spring mechanism 50 onto discharge conduit 10 at seal location S is sufficient to maintain discharge conduit inlet 12 sealed when mixing chamber 23 is either pressurized or depressurized. A actuator mechanism 60 is attached externally to micro-abrasive blasting device 55. Actuator mechanism 60 provides means for counteracting sealing force F_(S) applied to discharge conduit inlet 12 by spring mechanism 50.

[0083] As pressurized-gas is supplied to micro-abrasive blasting device 55 through gas-receiving port 35, mixing chamber 23 is pressurized. However, since discharge conduit inlet 12 is pinched shut at discharge conduit seal location S, there is no flow through the device. Since no flow exists, no abrasive-gas mixing occurs in mixing chamber 23.

[0084] Referring to FIG. 4B, actuation force F_(A) is applied to actuator mechanism 60 typically by means of the user's finger-touch. As actuation force F_(A) is applied to actuator mechanism 60, actuator mechanism 60 counteracts sealing force F_(S) applied by spring mechanism 50. Actuation force F_(A) is transferred from actuator mechanism 60 through the deformation of mixing chamber side wall 15 onto spring mechanism 50. As actuation force F_(A) generated by actuator mechanism 60 surmounts sealing force F_(S) generated by spring mechanism 50, discharge conduit inlet 12 is un-pinched at discharge conduit seal location S. The un-pinching of discharge conduit inlet 12 permits pressurized-gas inside mixing chamber 23 to instantly flow through discharge conduit 10. As flow is initiated, particulate matter 20 instantaneously mixes with the flowing gas and is dispensed through discharge conduit 10 to strike target material 40.

[0085] As actuation force F_(A) is reduced, sealing force F_(S) applied by spring mechanism 50 increasingly pinches discharge conduit 10 at seal location S until discharge conduit 10 is shut and flow is no longer possible.

[0086] A flow-control mechanism 65 is defined by the interaction of spring mechanism 50 and actuator mechanism 60 to regulate the flow through discharge conduit 10. Flow-control mechanism 65 provides means for the adjustment of discharge conduit 10 cross-sectional area opening at discharge conduit control location C. When discharge conduit 10 is un-pinched at control location C so the cross-sectional area of discharge conduit 10 is minimal, low flow-rate is provided through discharge conduit 10. When discharge conduit 10 is un-pinched at control location C so the cross-sectional area at discharge conduit 10 is maximized, high flow-rate is provided through discharge conduit 10. Therefore in general terms, flow-control mechanism 65 provides means for regulating the flow through micro-abrasive blasting device 55 via control of the flow through discharge conduit 10 at control location C.

[0087] The embodiment of FIG. 4 has the significant enhancement that it eliminates components with relative motion that are also required to act as a pressure seal. This is accomplished by making chamber side wall 15 compliant so it is able to deform. The ability of chamber side wall 15 to deform allows the chamber side wall 15 to act as diaphragm that is able to transfer displacement from the externally disposed actuator mechanism 60 to internally disposed spring mechanism 50. Of course chamber first side wall 17 and chamber second side wall 30 can also be utilized in this manner. In cases where mixing chamber 23 is made of none-compliant material, a similar diaphragm effect can be achieved by using compliant materials at mixing chamber 23 wall portions that require deformation.

[0088] Although the embodiment of FIG. 4 is an improvement over prior art, it has the drawback that spring mechanism 50 is disposed internally to mixing chamber 23. More specifically, particulate matter 20 interferes with the smooth operation of spring mechanism 50 resulting in suspect flow-regulation reliability, and spring mechanism 50 interferes with the mixing action within mixing chamber 23. Additionally, since spring mechanism 50 is internal to mixing chamber 23, spring mechanism 50 reduces the available space for particulate matter 20 within mixing chamber 23.

[0089] The embodiment of FIG. 5 addresses this drawback by disposing spring mechanism 50 externally to mixing chamber 23 and by disposing discharge port 45 in mixing chamber side wall 15. In this embodiment, discharge conduit 10 is also utilized as spring mechanism 50 and actuator mechanism 60 whereby discharge conduit 10 is pre-loaded to provide sealing force F_(S) at discharge conduit inlet 12. Sealing force F_(S) assures that discharge conduit inlet 12 abuts mixing chamber side wall 15 to provide a seal at discharge conduit seal location S. Referring to FIG. 5B, as actuation force F_(A) is applied onto discharge conduit 10, discharge conduit 10 bows to produce a rotation about discharge port 45 thereby generating the displacement of discharge conduit inlet 12. The displacement of discharge conduit inlet 12 removes the seal at seal location S, thereby permitting flow through micro-abrasive blasting device 55. The rotation about discharge port 45 can be achieved via deformation of mixing chamber side wall 15.

[0090] This embodiment, as the embodiment of FIG. 4, has no relative movement of surfaces that are exposed to abrasive material. Additionally it supports a discharge conduit 10 configuration that provides more particulate matter 20 storage space and less mixing resistance. These benefits are attained via the routing of discharge conduit 10 through discharge port 45 located on mixing chamber side wall 15.

[0091] Of course discharge conduit 10 can be formed in many shapes that provide the same functionality as shown in the embodiment of FIG. 5. For example, the direction of actuation force F_(A) can be reversed and discharge conduit inlet 12 can be made to abut the opposite surface of the chamber side wall 15; discharge conduit inlet 12 can be made to contact side wall 15 at another seal location S with respect to discharge port 45; and the movement of discharge conduit 10 with respect to discharge port 45 can be linear and/or rotational to provide the proper displacement at seal location S. Deformation of mixing chamber side wall 15 at discharge port 45 can be utilized to transfer external movement of discharge conduit 10 into internal displacements of discharge conduit 10.

[0092] Additionally, a multitude of discharge conduit 10 configuration can be generated that utilize discharge conduit 10 as spring mechanism 50 and actuator mechanism 60, as to achieve various forms of integral flow-control mechanism 65. As in the embodiment of FIG. 4, flow-control mechanism 65 provides means for regulating the opening of discharge conduit 10 at control location C, thereby providing means for controlling the flow through discharge conduit 10.

[0093]FIGS. 4 and 5 and prior art FIGS. 1, 2, and 3 each disclose different flow-control mechanisms yet are similar in that both sealing location S and control location C occur at discharge conduit inlet 12. It was determined through experimentation with many device configurations that it is challenging to implement integral flow-control mechanism 65 means that seal discharge conduit 10 precisely at discharge conduit inlet 12.

[0094] Therefore an advanced strategy was employed that physically de-couples the flow-control function from the function of preventing abrasive material entry into the discharge conduit. More specifically, the subsequent embodiments have a flow-control mechanism located on the discharge conduit downstream of the discharge conduit inlet as well as a mechanism at the discharge conduit inlet for preventing abrasive material from entering the discharge conduit.

[0095]FIG. 6 discloses an embodiment that eliminates the entry of particulate matter 20 into discharge conduit 10 when no flow exists, even though discharge conduit control location C is downstream of discharge conduit inlet 12. Similar to the prior art of FIG. 3, discharge conduit 10 is a combination of discharge conduit compliant segment 74 and discharge conduit firm segments 76. Flow-control mechanism 65 provides means for flow regulation at control location C on discharge conduit 10 downstream of discharge conduit inlet 12. The implementation of control location C externally to mixing chamber 23 provides for no relative movement between components that are exposed to particulate matter 20.

[0096] However, the embodiment of FIG. 6 supports a significant enhancement over prior art in that a flow-actuated discharge conduit seal 80 is located at seal location S. Flow-actuated discharge conduit seal 80 disposed at discharge conduit inlet 12 is depicted as a check-valve that is normally shut when no flow is present. When no flow is present, the operation of flow-actuated discharge conduit seal 80 eliminates the entry of particulate matter 20 into discharge conduit 10, for either when mixing chamber 23 is pressurized or depressurized. As shown in FIG. 6A, prior to device use flow-actuated discharge conduit seal 80 normally seals discharge conduit inlet 12 at seal location S, as flow-control mechanism 65 pinches discharge conduit 10 shut at control location C.

[0097] As shown in FIG. 6B, a pressurized-gas source connector 90 engages micro-abrasive blasting device 55 to deliver pressurized-gas to gas-delivery conduit 25. As mixing chamber 23 is pressurized via pressurized-gas source connector 90 and discharge conduit 10 is shut at control location C, flow-actuated discharge conduit seal 80 remains sealed. Referring to FIG. 6C, when mixing chamber 23 is pressurized and flow-control mechanism 65 means un-pinches discharge conduit 10 at control location C, flow pushes open the check-valve means of flow-actuated discharge conduit seal 80. Once flow-actuated discharge conduit seal 80 is opened, pressurized-gas inside mixing chamber 23 is able to normally flow through discharge conduit 10. As flow is initiated, particulate matter 20 instantaneously mixes with the flowing gas and is dispensed through discharge conduit 10 to strike target material 40. Once flow is terminated, sealing force F_(S) automatically repositions the check-valve means of flow-actuated discharge conduit seal 80 to seal discharge conduit 10, as shown in FIGS. 6A and 6B.

[0098] Since in this embodiment flow-control mechanism 65 only provides means for regulating the opening and closing of discharge conduit 10, flow-control mechanism 65 provides a shutting force F_(T) onto discharge conduit 10. Sealing force F_(S) for this embodiment is provided separately by flow-actuated discharge conduit seal 80, where sealing force F_(S) is just sufficient to restrict the entry of particulate matter 20 into discharge conduit 10 when no flow is present. Flow through micro-abrasive blasting device 55 provides the counteracting force to sealing force F_(S) at seal location S.

[0099] Check-valve mechanisms are usually utilized to restrict flow to a single direction; however, in this specific application there is no need for restricting flow-direction. The only requirement for flow-actuated discharge conduit seal 80 is to provide means to restrict particulate matter 20 entry into discharge conduit 10 when there is no flow and to open when flow is present. FIG. 7 depicts a flow-actuated discharge conduit seal 80 that is made of compliant material. Referring to FIG. 7B, the compliant seal at discharge conduit inlet 12 is flow-actuated since it deforms to permit flow into discharge conduit 10 thereby forming flow-actuated discharge conduit seal 80. As shown in FIG. 7A, when no flow is present flow-actuated discharge conduit seal 80 automatically assumes its original shape due to its material properties and resumes to restrict the entry of particulate matter 20 into discharge conduit 10.

[0100] Of course many other types of mechanisms can be used to achieve the objective of flow-actuated discharge conduit seal 80 at seal location S. Flow-actuated discharge conduit seal 80 means may be integrated into and/or made contiguous with discharge conduit 10. Additionally, although the location of flow-actuated discharge conduit seal 80 is optimally disposed at discharge conduit inlet 12, it can also be positioned downstream of discharge conduit inlet 12 with some degradation in effectiveness. The degradation in effectiveness is due to the fact that the further flow-actuated discharge conduit seal 80 is disposed downstream of discharge conduit inlet 12, the more space there is for particulate matter 20 to accumulate within discharge conduit 10, specifically between flow-actuated discharge conduit seal 80 and discharge conduit inlet 12.

[0101] Referring to FIG. 8, flow-actuated discharge conduit seal 80 is also usable and beneficial to devices with no flow-control mechanism 65 means on discharge conduit 10. The embodiment of FIG. 8 is a significant improvement to abrasive devices that rely solely on flow-control mechanisms upstream of the mixing chamber, since it provides means for restricting particulate matter 20 from entering discharge conduit 10. This advantage is cultivated further in the disclosure of the preferred embodiment of this application.

[0102] The embodiment of FIG. 9 is functionally identical to the device of FIG. 6, yet provides more particulate matter 20 storage space and less mixing resistance. These benefits are attained via the routing of discharge conduit 10 through discharge port 45 located on mixing chamber side wall 15. As with the embodiment of FIG. 6, flow-control mechanism 65 provides means for regulating the flow through micro-abrasive blasting device 55 at control location C, while flow-actuated discharge conduit seal 80 at seal location S provides means for preventing particulate matter 20 from entering discharge conduit 10 when no flow is present. Discharge conduit 10 is a combination of discharge conduit compliant segment 74 and discharge conduit firm segments 76.

[0103] As shown in FIG. 9A, prior to use flow-actuated discharge conduit seal 80 normally seals discharge conduit inlet 12 as flow-control mechanism 65 pinches discharge conduit 10 shut at control location C. As shown in FIG. 9B, as mixing chamber 23 is pressurized via a pressurized-gas source connector 90, flow-actuated discharge conduit seal 80 continues to seal discharge conduit inlet 12. As shown in FIG. 9C, as flow-control mechanism 65 un-pinches discharge conduit 10 at control location C, flow is possible through micro-abrasive blasting device 55. The flow opens flow-actuated discharge conduit seal 80 at seal location S to let particulate-gas mixture through discharge conduit inlet 12. Once flow is terminated, sealing force F_(S) automatically returns flow-actuated discharge conduit seal 80 to its normal sealing state, as show in FIGS. 9A and 9B.

[0104]FIG. 10 is functionally identical to the embodiment of FIG. 9 but provides significant structural simplifications. The embodiment of FIG. 10 disposes discharge port 45 and flow-actuated discharge conduit seal 80 in mixing chamber side wall 15, thereby eliminating the need for the internal segment of discharge conduit 10. Discharge conduit 10 extends externally to mixing chamber 23 from discharge port 45 to discharge conduit outlet 70. Of course flow-actuated discharge conduit seal 80 could also be integrated into mixing chamber side wall 15 at discharge port 45 as a contiguous element.

[0105] This embodiment provides the maximum space for particulate matter 20 within mixing chamber 23 and the least interference by discharge conduit 10 to the gas-particulate mixing. Additionally, the embodiment of FIG. 10 provides a reduction in the number of components and a significant assembly advantage since the internal segment of discharge conduit 10 is eliminated.

[0106] Referring to FIG. 11, this embodiment is also functionally identical to the embodiment of FIG. 9, but differs in that discharge port 45 is disposed in mixing chamber second end wall 30. Discharge conduit 10 extends from discharge conduit inlet 12, through discharge port 45, to discharge conduit outlet 70. Mixing chamber second end wall 30 supports both gas-receiving port 35 and discharge port 45. As with the embodiment of FIG. 9, flow-control mechanism 65 provides means for regulating the flow through micro-abrasive blasting device 55 at control location C, while flow-actuated discharge conduit seal 80 at seal location S provides means for preventing particulate matter 20 from entering discharge conduit 10 when no flow is present.

[0107] This embodiment is an improvement since a single chamber wall supports both interface-ports to mixing chamber 23, making the device simpler to manufacture. Since mixing chamber second end wall 30 supports both gas-delivery conduit 25 and the internal segment of discharge conduit 10, when mixing chamber second end wall 30 is made removable, a single insertion of mixing chamber second end wall 30 completes mixing chamber 23.

[0108] The embodiment of FIG. 12 provides additional evidence of the advantage of disposing discharge port 45 in mixing chamber second end wall 30. The routing of discharge conduit 10 next to mixing chamber second end wall 30 provides means for an external control mechanism, such as a foot-pedal, to act as a flow-control mechanism 65 at control location C. Referring to FIG. 12A, prior to use micro-abrasive blasting device 55 supports no flow-control mechanism on discharge conduit 10, but employs flow-actuated discharge conduit seal 80 at seal location S. Flow-actuated discharge conduit seal 80 assures that no particulate matter 20 can enter discharge conduit 10 prior to use.

[0109] As shown in FIG. 12B, a pressurized-gas source connector 90 engages micro-abrasive blasting device 55 to deliver pressurized-gas to gas-delivery conduit 25. An external actuator mechanism 95 is disposed within pressurized-gas source connector 90 and upon engagement with micro-abrasive blasting device 55 normally pinches discharge conduit 10 shut via application of shutting force F_(T) onto discharge conduit 10. As mixing chamber 23 is pressurized via pressurized-gas source connector 90 and discharge conduit 10 is shut at control location C, flow-actuated discharge conduit seal 80 remains sealed.

[0110] Referring to FIG. 12C, upon activation of external actuator mechanism 95 via a foot-pedal depression for instance, actuation force F_(A) is provided to counteract shutting force F_(T). Consequently external actuator mechanism 95 retracts causing flow-control mechanism 65 to un-pinch discharge conduit 10. When mixing chamber 23 is pressurized and flow-control mechanism 65 means un-pinches discharge conduit 10 at control location C, flow pushes open flow-actuated discharge conduit seal 80 and permits pressurized-gas inside mixing chamber 23 to instantly flow through discharge conduit 10. As flow is initiated, particulate matter 20 instantaneously mixes with the flowing gas and is dispensed through discharge conduit 10 to strike target material 40. Once flow is terminated, sealing force F_(S) automatically returns flow-actuated discharge conduit seal 80 means to its normal sealing state, as show in FIGS. 12A and 12B.

[0111] Although external actuator mechanism 95 is shown as integral to pressurized-gas source connector 90, it can also be implemented as a separate mechanism. Additionally, external actuator mechanism 95 may be made to directly actuate a flow-control mechanism means on discharge conduit 10 that is integral to micro-abrasive blasting device 55. External actuator mechanism 95 can be remotely manipulated pneumatically, electrically, mechanically, or by other design choices. External actuator mechanism 95 may also provide means for translating foot-pedal depression amplitudes into magnitudes of discharge conduit 10 pinch, thereby providing the user with a range of operational flow regulation.

[0112] The embodiment of FIG. 12 also demonstrates the innovation of making discharge conduit 10 or a segment of discharge conduit 10 contiguous with mixing chamber side wall 15. Making a segment of discharge conduit 10 contiguous with mixing chamber 23 walls provides integration that leads to additional assembly simplification.

[0113] Referring to the preferred embodiment of FIG. 13, micro-abrasive blasting device 55 supports operation by either a integral flow-control mechanism 65 _((i)) or a external flow-control mechanism 65 _((e)). As shown in FIG. 13A, integral flow-control mechanism 65 _((i)) is mounted to micro-abrasive blasting device 55. Referring to FIG. 13B, external flow-control mechanism 65 _((e)) is provided via engagement of a pressurized-gas source connector 90. Therefore this embodiment supports integral flow-control mechanism 65 _((i)) means which applies shutting force F_(T(i)) to discharge conduit 10 at control location C_((i)), and external flow-control mechanism 65 _((e)) means which applies shutting force F_(T(e)) to discharge conduit 10 at control location C_((e)).

[0114] The micro-abrasive blasting device 55 of FIG. 13 can be operated either by application of actuation force F_(A(e))to external flow-control mechanism 65 _((e)) via remote actuator mechanism 95 or by application of actuation force F_(A(i)) to integral flow-control mechanism 65 _((l)) via actuator mechanism 60. When ready for use, the user selects to utilize one flow-control mechanism 65 and bypass the other, based on the user's operational preference for an integral or an external flow regulation method, i.e. finger-touch control or foot-pedal control, respectively.

[0115] The embodiment of FIG. 13 also provides further structural simplification, where mixing chamber second side wall 30 supports means for flow-actuated discharge conduit seal 80. This enhancement further reduces the number of components thereby simplifying the assembly. Additionally, the elimination of the internal segment of discharge conduit 10 within mixing chamber 23 eliminates any mixing interference.

[0116] A further improvement disclosed by this preferred embodiment, is that a segment of discharge conduit 10 is integrated into mixing chamber second side wall 30. Mixing chamber second side wall 30 acts as a conduit that routes discharge conduit 10 through discharge port 45 externally to mixing chamber 23 through mixing chamber side wall 15. This device is simple to assembly since the insertion of a removable mixing chamber second side wall 30 completes discharge conduit 10 and mixing chamber 23 simultaneously.

[0117] The preferred embodiment of FIG. 14 is functionally identical to the preferred embodiment of FIG. 13, yet supports an optimized configuration for inexpensive disposable devices. This preferred embodiment eliminates redundant components by providing a single flow-control mechanism 65 that is usable via integral or remote means. The embodiment of FIG. 14A is a micro-abrasive blasting device 55 with means for flow-actuated discharge conduit seal 80 located at seal location S. Prior to use micro-abrasive blasting device 55 supports no integral flow-control mechanism 65 means on discharge conduit 10 and therefore has no control location C. Flow-actuated discharge conduit seal 80 assures that no particulate matter 20 can enter discharge conduit 10 prior to use.

[0118] Referring to FIG. 14B, pressurized-gas is provided via a pressurized-gas source connector 90 that supports means for a flow-control mechanism 65. As pressurized-gas source connector 90 connects to micro-abrasive blasting device 55, flow-control mechanism 65 engages discharge conduit 10 at control location C. Flow-control mechanism 65 acts to normally shut discharge conduit 10 by applying shutting force F_(T) at control location C.

[0119] A integral actuator mechanism 98 is located externally to mixing chamber 23 with means to engage flow-control mechanism 65. Flow-control mechanism 65 can be actuated via external actuator mechanism 95 or integral actuator mechanism 98. As mixing chamber 23 is pressurized, shutting force F_(T) at control location C prevents flow through discharge conduit 10, and flow-actuated discharge conduit seal 80 restricts entry of particulate matter 20 into discharge conduit 10.

[0120] Referring to FIG. 14C, as mixing chamber 23 is pressurized flow-control mechanism 65 means may be actuated via integral actuator mechanism 98 or external actuator mechanism 95. Integral actuator mechanism 98 provides means for transferring actuation force F_(A(l)) to flow-control mechanism 65 located on pressurized-gas source connector 90. If the user selects to regulate micro-abrasive blasting device 55 using a foot-pedal, actuation force F_(A(e)) actuates flow-control mechanism 65 via external actuator mechanism 95. If the user selects to regulate micro-abrasive blasting device 55 using finger-touch control, actuation force F_(A(i)) is applied to flow-control mechanism 65 via integral actuator mechanism 98.

[0121] Since there is only a single control location C, there is no need for the user to by-pass a flow-control mechanism, as required by the preferred embodiment of FIG. 13. Integral actuation force F_(A(i)) or external actuation force F_(A(e)) counteract shutting force F_(T), thereby actuating flow-control mechanism 65. When flow-control mechanism 65 means un-pinches discharge conduit 10 at control location C, flow pushes flow-actuated discharge conduit seal 80 open and permits pressurized-gas inside mixing chamber 23 to normally flow through discharge conduit 10. As flow is initiated, particulate matter 20 instantaneously mixes with the flowing gas and is dispensed through discharge conduit outlet 70 to strike target material 40.

[0122] As actuation force F_(A(i)) or actuation force F_(A(e)) is reduced, shutting force F_(T) increasingly pinches discharge conduit 10 at control location c until discharge conduit 10 is shut and flow is no longer possible. As flow is terminated, sealing force F_(S) automatically returns flow-actuated discharge conduit seal 80 to its normal sealing state, as show in FIGS. 14A and 14B.

[0123] From the description above, the following advantages of the present invention become evident:

[0124] (a) Providing a discharge port at a variety of mixing chamber walls

[0125] (I) facilitates a configuration that has minimal or no space consumed by the discharge conduit, thereby forming a device with more space in the mixing chamber for abrasive material;

[0126] (II) facilitates a configuration that has minimal or no discharge conduit presence within the mixing chamber, thereby reducing or eliminating interference by the discharge conduit on the mixing process;

[0127] (III) facilitates the positioning of the flow-control mechanism in the vicinity of the pressurized-gas connector, thereby making the device usable with an external flow-control mechanisms such as a food-pedal;

[0128] (IV) provides a configuration that has interface-ports disposed in a single chamber wall, thereby making the device simpler

[0129] (1) to manufacture and assemble, and

[0130] (2) to replenish when made refillable.

[0131] (V) facilitates a configuration where discharge conduit is integral and/or contiguous to mixing chamber walls, thereby making the device simpler to manufacture and assemble.

[0132] (VI) facilitates the elimination of redundant components, thereby providing an optimized configuration for inexpensive disposable devices.

[0133] (b) Providing a flow-actuated discharge conduit seal

[0134] (I) eliminates the need for the flow-control mechanism to act as a seal, thereby enabling the placement of the flow-control mechanism anywhere along the discharge conduit;

[0135] (II) eliminates the need for the flow-control mechanism to act upon the discharge conduit inlet, thereby making a device that

[0136] 1) operates more reliably without relative movement of components that are exposed to the abrasive material;

[0137] 2) operates more reliably without relative movement of components that act as pressure seals;

[0138] 3) has more space for abrasive material since no flow-control mechanism internal to the mixing chamber is needed.

[0139] 4) is able to operate with either external and integral flow-control mechanisms.

[0140] (III) eliminates the entry of abrasive material when no flow exists, thereby

[0141] 1) eliminating puffs of abrasive during operation start-up;

[0142] 2) providing a device with better operational performance.

[0143] (IV) provides a reliable method for preventing particulate matter entry into the discharge conduit for the life of the device.

[0144] While the invention has been described, disclosed, illustrated and shown in various terms or certain embodiments or modifications which it has assumed in practice, the scope of the invention is not intended to be, nor should it be deemed to be, limited thereby and such other modifications or embodiments as may be suggested by the teachings herein are particularly reserved especially as they fall within the breadth and scope of the claims here appended.

[0145] Summary, Ramification, and Scope

[0146] The present invention accomplishes the above-stated objectives, as well as others, as may be determined by a fair reading and interpretation of the entire specification.

[0147] Accordingly, the reader will see that the present invention is a superior micro-abrasive blasting device due to its versatile flow-control and flow-actuated discharge conduit seal located on the discharge conduit. The disclosed device provides precise flow-control with both finger-touch and foot-pedal regulation.

[0148] The flow-control method provides for the continuous pressurization of the mixing chamber that yields instantaneous flow start-up response and instantaneous flow shut-off response. The flow-actuated discharge conduit seal is optimally disposed at discharge conduit inlet and is normally shut when no flow is present. The operation of the flow-actuated discharge conduit seal prevents the entry of abrasive material into the discharge conduit when no flow is present, yet opens when there is flow through the micro-abrasive blasting device. Once flow is terminated, the flow-actuated discharge conduit seal automatically returns to its normal sealing state.

[0149] Additionally, the reader will recognize that the preferred device offers superior operational performance by eliminating puffs of abrasive during operation start-up, while providing precise gas-abrasive flow regulation so a single device is able to operate in a wide range of applications, from light etching to drilling and cutting.

[0150] Furthermore, the present invention has the additional advantages in that

[0151] it provides a simple device where the discharge conduit deforms to provide a stationary discharge conduit outlet.

[0152] it provides a device with increased chamber space for abrasive material and reduced mixing resistance.

[0153] it provides a device with flow-control means that has a reduced number of components so device manufacturing and assembly complexity is reduced.

[0154] Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given. 

What I claim as my invention is:
 1. A micro-abrasive blasting device, comprising: a chamber having a side wall, a first end wall at one end of the chamber and a second end wall at an opposite end of the chamber; a gas-receiving port in said second end wall; a gas-delivery conduit disposed within said chamber and extending in fluid communications from said gas-receiving port towards said first end wall; a discharge port in said chamber wall; a discharge conduit elongated from a discharge conduit inlet to a discharge conduit outlet and extending in fluid communications through said discharge port external to the chamber; a quantity of particulate matter disposed within the chamber; wherein means for flow-control is located on said discharge conduit.
 2. The apparatus, according to claim 1, wherein: the discharge conduit extends from the discharge port internal to the chamber.
 3. The apparatus, according to claim 2, wherein: means for a flow-actuated seal is disposed on the discharge conduit.
 4. The apparatus, according to claim 3, wherein: said means for a flow-actuated seal is disposed at said discharge conduit inlet.
 5. The apparatus, according to claim 1, wherein: means for a flow-actuated seal is located on the discharge conduit.
 6. The apparatus, according to claim 5, wherein: said means for a flow-actuated seal is disposed at said discharge conduit inlet.
 7. The apparatus, according to claim 1, wherein: means for a flow-actuated seal is disposed at the discharge port.
 8. The apparatus, according to claim 7, wherein: said means for a flow-actuated seal is contiguous and/or integral with the discharge port and/or chamber wall.
 9. The apparatus, according to claim 1, wherein: a segment of the discharge conduit is contiguous and/or integral with at least one chamber wall.
 10. The apparatus, according to claim 1, wherein: the chamber second end wall is removable.
 11. The apparatus, according to claim 1, wherein: said flow-control means prevents depressurization of the chamber.
 12. The apparatus, according to claim 1, wherein: deformation of the discharge conduit provides means for flow-control.
 13. The apparatus, according to claim 1, wherein: deformation of the discharge conduit provides means for controlling the opening and closing of the discharge conduit.
 14. The apparatus, according to claim 1, wherein: deformation of the discharge conduit provides actuation force means for flow-control.
 15. The apparatus, according to claim 1, wherein: deformation of the discharge conduit provides means for maintaining said discharge conduit outlet stationary.
 16. The apparatus, according to claim 1, wherein: means for flow-control is provided via the deformation of the chamber wall.
 17. The apparatus, according to claim 1, wherein: a flow-control mechanism is integral to said micro-abrasive blasting device.
 18. The apparatus, according to claim 1, wherein: a external actuation mechanism engages said micro-abrasive blasting device to provide means for flow-control.
 19. The apparatus, according to claim 18, wherein: said external actuation mechanism is disposed in and/or integral to a pressurized-gas source connector.
 20. A micro-abrasive blasting device, comprising: a chamber having a side wall, a first end wall at one end of the chamber and a second end wall at an opposite end of the chamber; a gas-receiving port in said second end wall; a gas-delivery conduit disposed within said chamber and extending in fluid communications from said gas-receiving port towards said first end wall; a discharge port in said chamber wall; a discharge conduit elongated from a discharge conduit inlet to a discharge conduit outlet and extending in fluid communications through said discharge port external to the chamber; a quantity of particulate matter disposed within the chamber; wherein said discharge conduit supports means for a flow-actuated seal.
 21. The apparatus, according to claim 20, wherein: the discharge conduit extends from the discharge port internal to the chamber.
 22. The apparatus, according to claim 20, wherein: said means for a flow-actuated seal is disposed at said discharge conduit inlet.
 23. The apparatus, according to claim 20, wherein: said means for a flow-actuated seal is disposed at the discharge port.
 24. The apparatus, according to claim 23, wherein: the means for a flow-actuated seal is contiguous and/or integral with the discharge port and/or chamber wall.
 25. The apparatus, according to claim 20, wherein: a segment of the discharge conduit is contiguous and/or integral with at least one chamber wall.
 26. The apparatus, according to claim 20, wherein: the chamber second end wall is removable.
 27. The apparatus, according to claim 20, wherein: means for flow-control is provides via deformation of the discharge conduit.
 28. The apparatus, according to claim 27, wherein: said flow-control means prevents depressurization of the chamber.
 29. The apparatus, according to claim 27, wherein: deformation of the discharge conduit provides means for controlling the opening and closing of the discharge conduit.
 30. The apparatus, according to claim 27, wherein: deformation of the discharge conduit provides actuation force means for flow-control.
 31. The apparatus, according to claim 27, wherein: deformation of the discharge conduit provides means for maintaining the discharge conduit outlet stationary.
 32. The apparatus, according to claim 27, wherein: means for flow-control is provided via the deformation of chamber wall.
 33. The apparatus, according to claim 27, wherein: a flow-control mechanism is integral to said micro-abrasive blasting device.
 34. The apparatus, according to claim 27, wherein: a external actuation mechanism engages said micro-abrasive blasting device to provide means for flow-control.
 35. The apparatus, according to claim 34, wherein: said external actuation mechanism is disposed in and/or integral to a pressurized-gas source connector.
 36. The apparatus, according to claim 34, wherein: a integral actuator mechanism provides actuation means to said external actuation mechanism.
 37. A method for flow-control of a micro-abrasive blasting device, comprising: a chamber having a side wall, a first end wall at one end of the chamber and a second end wall at an opposite end of the chamber; a gas-receiving port in said second end wall; a gas-delivery conduit disposed within said chamber and extending in fluid communications from said gas-receiving port towards said first end wall; a discharge port in said chamber wall; a discharge conduit elongated from a discharge conduit inlet to a discharge conduit outlet and extending in fluid communications through said discharge port external to t he chamber; a quantity of particulate matter disposed within the chamber; means for deforming said discharge conduit; wherein deformation of the discharge conduit provides means for controlling the flow through the discharge conduit while maintaining said discharge conduit outlet stationary.
 38. The method, according to claim 37, wherein: a flow-actuated discharge conduit seal restricts the entry of said particulate matter into the discharge conduit when no flow is present.
 39. A method for preventing the entry of particulate matter into a discharge conduit of a micro-abrasive blasting device, comprising: a chamber having a side wall, a first end wall at one end of the chamber and a second end wall at an opposite end of the chamber; a gas-receiving port in said second end wall; a gas-delivery conduit disposed within said chamber and extending in fluid communications from said gas-receiving port towards said first end wall; a discharge port in said chamber wall; a discharge conduit elongated from a discharge conduit inlet to a discharge conduit outlet and extending in fluid communications through said discharge port external to the chamber; a quantity of particulate matter disposed within the chamber; means for a flow-actuated seal disposed on said discharge conduit; wherein said flow-actuated seal restricts the entry of said particulate matter into the discharge conduit when no flow is present.
 40. The method, according to claim 39, wherein: deformation of the discharge conduit provides means for controlling the flow through the discharge conduit while maintaining said discharge conduit outlet stationary. 